In this post, Carolina Sartorio discusses her recent article in the Causation in War Symposium in Journal of Applied Philosophy on how degrees of causation can (and cannot) bear on liability to harm.

The recent literature on the ethics of war draws heavily on the concept of causation. Your liability to be attacked during a war, some suggest, depends on the extent of your causal contribution to an unjust threat. Prominent theorists like Jeff McMahan and Cecile Fabre embrace a principle of civilian immunity on this basis: they claim that civilians (unlike soldiers) aren’t liable to attack because their causal contributions to an unjust war are typically very minimal. These ideas rest on an important assumption: that causation comes in degrees. But, is this assumption true? In my article, I argue against it. I claim that the appearance that causation comes in degrees is an illusion that can be explained away.

The main argument

My argument boils down to this:

  • If causal contributions came in degrees, there would be multiple, equally plausible criteria that could be used to measure the extent of those contributions.
  • But these different criteria result in some conflicting verdicts that it’s impossible to adjudicate on principled grounds (which is unacceptable).


  • Causal contributions don’t come in degrees.

What are the multiple criteria the argument refers to? I focus on the following two:

Sufficiency: how close a cause comes to providing a sufficient condition for its effect.

Necessity: how close a cause comes to providing a necessary condition for its effect.

To illustrate the two criteria, and how they can result in incompatible verdicts, imagine that you are making a bean dish for dinner. Although beans are a main ingredient of this dish, any kind would do (black beans, red beans, pinto beans…). So, you just pick the first kind you find in the pantry—say, black beans. On the other hand, the dish calls for a specific herb that gives it a distinctive taste—say, cilantro—and thus is not replaceable with other herbs.

The two criteria say conflicting things about the contribution that each ingredient makes to the dish. While the black beans are a more sizeable, though unnecessary or replaceable, ingredient, the cilantro is a less sizeable, though necessary or irreplaceable, ingredient. Thus, the black beans make “more of a contribution” in the sense tracked by Sufficiency, but the cilantro makes “more of a contribution” in the sense tracked by Necessity.

As a result, a puzzle arises if you still want to hold that causation comes in degrees. For now you face this question: Which ingredient makes more of a contribution, all things considered: the black beans or the cilantro? More generally: What makes something “more of a cause”, having made a more sizeable but unnecessary contribution, or having made a less sizeable but necessary contribution?

In the article, I argue that the best solution to this puzzle is to say that questions of this kind don’t make sense. Being a cause is a matter of making some contribution or other, by joining forces with other contributing causes to collectively bring about an outcome. And this is not something that can be cashed out in terms of degrees, for reasons that our puzzle helps bring out. The appearance that causal contributions come in degrees is an illusion, and, like optical illusions, it can be explained away. That is to say, it’s possible to explain how it arises, and why it was easy to be misled. (The paper discusses different strategies for doing this, depending on the particular type of case in question.)

Consequences for the ethics of war and defensive harming

If I’m right and causal contributions don’t come in degrees, then this has important implications for the ethics of war and defensive harming. Any contributions to unjust wars will be indistinguishable on purely causal grounds. Thus, if we still want to distinguish between, say, the liability of contributing civilians and soldiers in a war, we’ll have to find other ways to do that. Appealing to the extent of their causal contributions to an unjust war is a dead end.

The Journal of Applied Philosophy is a unique forum for philosophical research that seeks to make a constructive contribution to problems of practical concern. Open to the expression of diverse viewpoints, it brings the identification, justification, and discussion of values to bear on a broad spectrum of issues in environment, medicine, science, policy, law, politics, economics and education. The journal publishes in all areas of applied philosophy, and posts accessible summaries of its recent articles on Justice Everywhere.